(1) Field of the Invention
The present invention relates to a technology of managing duplication of contents in the use of the contents in a networked environment.
(2) Description of the Related Art
Conventionally, there are several known techniques to restrict an unlimited duplication of contents. One example is copy generation management that prohibits a copy or duplication of a duplicated content (a third generation duplication). Another example is disclosed in Japanese unexamined patent application publication No. 2000-357213 that requires mutual authentication to be performed between a transmitting end and a receiving end and allows duplication of a content according to the authentication result.
The above copy generation management technique and the one disclosed in the above publication gazette are mainly applied to a system composed of a recording apparatus and a recording medium. Examples of such a recording apparatus include a personal computer and a recorder, while examples of such a recording medium include a DVD and an SD card. In such a system, a recording apparatus collectively manages control information that is used, for example, to restrict the number of times that contents can be duplicated.
Unfortunately, however, the above conventional techniques involve the following problems when applied to distributing contents via a network.
Suppose, for example, contents are used in a home network environment in which a plurality of devices are mutually connected. In this case, a recording apparatus is the only apparatus that manages control information that is used, for example, to restrict the number of times each content can be duplicated. Consequently, in order to duplicate a content, all the other devices need to make a request to the recording apparatus, and then receive the content from the recording apparatus. In other words, any content cannot be transmitted unless the recording apparatus is the transmitting end. Such usage of contents in a home network environment is inconvenient for users and thereby fails to meet the users' need for high usability.